PAE requires a dedicated 1G of kernel virtual memory. This results in the decision of either applying the 4G/4G sharing or the 2G/2G split. Note that it's easier to allow 1G for PAE, 1G for kernel and 2G for userspace (2G/2G). This is a major bug and needs to be fixed in the next commit.
In the new c++ branch, the Autotools(i.e., configure and make) build system has been replaced with CMake (CMakefiles and make). This change is only temporary, and both are being (albeit cumbersomely) maintained. Future steps would be to decide one to keep and discard the other (probably keeping Cmake and archiving Autotools).